This project proposes to study the regulation of mitochondrial membrane assembly using mutants of Neurospora crassa isolated in previous studies. Studies to be carried out on the cni-1 mutant include determining the mechanisms of energy metabolism, studying the mechanism of cyanide-insensitive respiration and investigating the morphology of cni-1 mitochondria in the electron microscope. Attempts will also be made to determine the mechanism of regulation of membrane assembly when stationary phase cells are transferred to log phase growth. Studies on the genetics of the cyanide-insensitive pathway will be carried out by studying mutants isolated by an established procedure. These mutants will be studied by complementation analysis and mapped. Studies will also be carried out on the components of Neurospora crassa that are detectable by electron spin resonance. In addition to these studies, experiments will be carried out to study the regulation of mitochondrial function during the growth cycle. BIBLIOGRAPHIC REFERENCES: Klein, J.L., D.L. Edwards and S. Werser (1975) Regulation of mitochondrial membrane assembly in Neurospora crassa. Transient expression of a respiratory mutant phenotype. J. Biol. Chem. 250:5852-5858. Edwards, D.L. and E. Rosenberg (1976) Regulation of cyanide-insensitive respiration in Neurospora crassa. (Eur. J. Biochem.) (In press).